Buildings are always subjected to stress and strain forces due to expansion and contraction conditions attendant environmental temperatures, irregular foundation conditions, and distortion forces generated, for example, by means of earthquakes. It has therefore been conventional practice, when erecting interior building structures, to provide gap portions or regions between sections of the interior building structures so as to effectively absorb or accommodate the expansion and contraction conditions occurring within the building, thereby effectively preventing destruction of the building, or regions thereof, as a result of the existence of such expansion and contraction conditions and the forces, stresses, and strains generated thereby.
Accordingly, in connection with the finishing or completion of the interior structures of buildings, the aforenoted gap portions must be covered by means of expansion joint covers which can in fact accommodate both expansion and contraction conditions. As illustrated within FIG. 3, there is disclosed a conventional expansion joint system which includes a cover plate 51 which is engaged upon a pair of laterally spaced edge frames 50 which are, in turn, fixed to end portions a,a of two buildings separated by means of a gap G. Free edge portions of a pair of laterally spaced ceiling sections or plates b,b are disposed upon laterally outward support surfaces 54 of the edge frames 50, and the cover plate 51, which is of the flat plate type having a width sufficiently large enough to encompass the edge frames 50 and also engage opposite surfaces of the ceiling sections or plates b,b, and thereby accommodate any expansion and contractions conditions attendant gap G, is fixed to a suspended metal fixture 52, expansibly interposed between the laterally spaced edge frames 50,50, by means of a threaded bolt 53, whereby the gap G is in fact covered.
However, in accordance with the construction features of the conventional system shown in FIG. 3, and in particular with respect to the provision of the cover plate 51, the width W of the cover plate 51 is seen to be substantially larger than the width dimension of the gap G. Consequently, there developed the problem that the cover plate 51 extending along the expansion joint or gap G aesthetically divided the designs of the interior wall surfaces of the buildings, such as, for example, those of the ceiling panels, vertical wall panels, and the like. The problem has become particularly acute in connection with expansion joints or gaps G provided in connection with the construction of large office buildings, or high-rise buildings, whereby a sense of interior design incompatibility resulted in some cases.